The invention set forth herein pertains to new and improved caster support structures. Such support structures may be regarded as, in effect, forming a part of a caster.
Technically, a caster may be regarded as a structure involving a small wheel mounted upon a swivel which is utilized under an object so as to facilitate movement of the object. The invention set forth in this specification is primarily concerned with casters which have a yoke serving to support a wheel on an axle extending between the ends of the arms of the yoke and having a mounting shaft extending from the base of the yoke.
Casters of this type are normally utilized by placing the shaft in a support or support structure attached to and/or carried by an object so that the base of he yoke rests upon an end of the support or support structure with the shaft on the caster extending upwardly into a cylindrical cavity in the support or support structure. Most commonly such shafts are provided with headed ends remote from the yokes to which they are attached and most commonly the support or support structures include a somewhat resilient retainer permitting the shaft to be inserted into the support or support structure so that the head on such a shaft "snaps" or "pops" past the retainer into an operative position.
A structure of this type will operate as a caster as a result of relative rotation of the base of the yoke against the ends of the support or support structure and as a result of the shaft fitting within the support or support structure so as to be capable of rotating relative to it. Such a shaft is employed primarily in order to prevent twisting or "cocking" about the axis of the shaft since such twisting or "cocking" would tend to interfere with the desired swivel action and/ or rotation of the wheel about the axis of the shaft. Frequently the degree of friction between the base of a yoke of a caster and the support or support structure will be sufficiently great so as to impede such rotation about the axis of the shaft employed.
As a result of this, it is conventional to utilize bearings such as roller bearings so that they are generally disposed between a yoke and a support or support member. It is considered disadvantageous to utilize such a bearing so that it is mounted directly upon a shaft and/or yoke since if a normally exposed part of a caster were to become damaged there would be danger of the bearing having to be replaced. In the past it is believed that it has been proposed to mount bearings used for the purpose described directly upon supports or support structures. It is considered that such efforts have been unsatisfactory because of difficulty in adequately and firmly mounting bearings in such supports or support structures.